System for protecting a coated medical implant

ABSTRACT

A system for protecting a coated reconfigurable medical implant is provided. This system may include a carrier device having a proximal end and a distal end and a reconfigurable deployable coated medical implant in physical communication with an implant carrying region of the carrier device. In this system the deployable medical implant may be coated with a coating positioned on an exposed surface of the deployable medical implant and the deployable medical implant may be reconfigurable from a first larger configuration to a second contracted configuration. For protecting the coating, the coated medical implant may be encased by a hollow deformable membrane when the deployable medical implant is in the first larger configuration and the membrane may define a cavity with a cross-section that is smaller than the external cross-section of the deployable medical implant. The medical implant may be crimped to its second contracted configuration while the hollow deformable membrane is in place.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.09/954,185 filed Sep. 18, 2001, and entitled PROTECTIVE MEMBRANE FORRECONFIGURING A WORKPIECE, now U.S. Pat. No. 6,805,703. The entiredisclosure of the '185 application is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention regards a system for deploying a coated medicalimplant. More specifically the present invention regards a system forprotecting the coating of a coated medical implant at a time prior tothe deployment of the medical implant from a medical device.

BACKGROUND

Articles of manufacture are regularly coated for numerous and varyingreasons. For example, they may be coated to protect them from theintrusive handling they can be subjected to during their manufacture andto protect them from the severe environmental conditions they canencounter after they are manufactured. In either circumstance, as wellas in others, damage to the coating of a workpiece, resulting from thehandling, mishandling or reconfiguration of the workpiece, is anunwanted result.

When the coating of a workpiece becomes scratched or otherwise damagedduring its manufacture, the scratches can promote the deterioration ofnot only the coating but also the workpiece itself by exposing theworkpiece's surface to its surroundings. For instance, should theworkpiece be employed in a corrosive environment, its errantly exposedsurface would be more vulnerable to corrosion than if its coating werecompletely intact.

Moreover, the scratches and inconsistencies in the coating of aworkpiece may also reduce the effectiveness of the finished product. Forexample, should the coating be used to uniformly deliver some type ofreleasable substance, inconsistencies in the coating can foster unevenand non-homogeneous delivery of the releasable substance to the deployedproduct's final surroundings.

An expandable coated stent is one specific example of the coatedworkpieces described above. Expandable stents are tube-like medicaldevices designed to support the inner walls of a vessel or lumen withinthe body of a patient. These stents are typically positioned within atargeted lumen of the body and then expanded to provide internal supportfor the lumen. These stents may be self-expanding or, alternatively, mayrequire external forces to expand them. In either case they aretypically deployed through the use of a catheter of some kind. Thesecatheters typically carry the stents at their distal end.

Due to the interaction of the stent with the inner walls of the lumen,stents have been coated to enhance their effectiveness. These coatingsmay, among other things, be designed to facilitate the acceptance of thestent into its applied surroundings or to facilitate the delivery oftherapeutic to the lumen and its surroundings. When the coating ishaphazardly applied or has somehow been removed during the stent'smanufacture, both the stent's useable life span and its effectivenesscan be reduced.

The coatings on these stent may be applied at various times during itslife cycle including during its manufacture, during its placement ontothe distal end of the delivery catheter, and contemporaneous with themedical procedure being performed. At each of these times the coatingmay be at risk of being scratched, damaged or otherwise removed from thesurface of the stent. For example, during their manufacture, stents areoften crimped onto the distal end of the delivery catheter. During thiscrimping the mechanical arms of a crimper may come in contact with thecoating of the stent as the arms act to reduce the diameter of thestent. This compressive contact can scratch, indent, wipe-off orotherwise breach the integrity of the coating.

SUMMARY OF THE INVENTION

A system for protecting a coated reconfigurable medical implant isprovided. This system may include a carrier device having a proximal endand a distal end and a reconfigurable deployable coated medical implantin physical communication with an implant carrying region of the carrierdevice. In this system the deployable medical implant may be coated witha coating positioned on an exposed surface of the deployable medicalimplant and the deployable medical implant may be reconfigurable from afirst larger configuration to a second contracted configuration. Forprotecting the coating, the coated medical implant may be encased by ahollow deformable membrane when the deployable medical implant is in thefirst larger configuration and the membrane may define a cavity with across-section that is smaller than the external cross-section of thedeployable medical implant. The medical implant may be crimped to itssecond contracted configuration while the hollow deformable membrane isin place.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a coated workpiece that was manufacturedwithout a protective membrane in place.

FIG. 2 is a side view of a coated workpiece that was manufactured inaccord with an embodiment of the present invention.

FIG. 3 is a side view of a coated implant that has an encasing hollowdeformable membrane surrounding it in accord with an alternativeembodiment of the present invention.

FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3.

FIG. 5 is a side view of the coated implant of FIG. 3 after it has beenreconfigured in accord with an alternative embodiment of the presentinvention.

FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 5.

FIG. 7 is a side view of an uncrimped stent on a catheter prior to itsinsertion into an encasing hollow deformable membrane in accord withanother alternative embodiment of the present invention.

FIG. 8 is a side view of the uncrimped stent of FIG. 7 after it has beeninserted into the deformable membrane in accord with another alternativeembodiment of the present invention.

FIG. 9 is a side view of the uncrimped stent of FIGS. 7-8 after thedeformable membrane has been placed around it in accord with anotheralternative embodiment of the present invention.

FIG. 10 is a side view of the covered stent of FIGS. 7-9 prior to itsinsertion into a crimping chamber in accord with another alternativeembodiment of the present invention.

FIG. 11 is a side view of a covered implant prior to its insertion intoa braided sleeve in accord with another alternative embodiment of thepresent invention.

FIG. 12 is a side view of an implant prior to its insertion into anencasing hollow deformable membrane in accord with another alternativeembodiment of the present invention.

DETAILED DESCRIPTION

FIG. 1 is a side view of a coated workpiece 10 that was manufacturedwithout the benefit of a protective membrane. As can been seen, thecoating 12 of the workpiece haphazardly covers the workpiece 10 and insome areas 11 the workpiece 10 is not covered at all. The missingcoating 12 from these removed areas 11 may have been errantly removedduring various manufacturing steps and may have even been deposited onboth the machinery and the personnel that handled the workpiece duringthese steps.

FIG. 2 is a side view of a coated workpiece 20 that was manufacturedusing a protective deformable membrane in accord with one embodiment ofthe present invention. As can be seen, the workpiece 20 has maintainedmost, if not all of its protective coating 21 with only a fewdepressions 22 evident on the workpiece's surface. With more of thecoating 21 intact the workpiece 20 may be better suited to perform itsdesired function after its is deployed for its ultimate use. Moreover,by employing an encasing membrane to protect the coating 21 during themanufacture of the workpiece 20 the loads placed on the workpiece may bemore evenly distributed across the coating 21 and the coating 21 may beless susceptible to contaminating everything that comes in contact withit.

FIG. 3 is a side view of a coated implant 35, having a coating 32 thatmay be protected by an encasing membrane in accord with an alternativeembodiment of the present invention. The coated implant 35 in thisembodiment, which is comprised of the implant 30 defined by its frame36, may be covered with a coating 32 that is in turn surrounded by anencasing hollow deformable membrane 31. This encasing deformablemembrane 31 may be used to protect the coating 32 during the crimping ofthe implant 30, during its other manufacturing steps, and during itssubsequent handling.

During the crimping of an implant two goals are in conflict, high forcesare desired to adequately secure the implant to the implant carryingregion of a catheter or other carrier device while reduced forces aredesired to prevent the smearing or removal of the coating on the implant30. By using a protective membrane 31 around the coating the damagecaused by the compressive forces necessary to crimp the implant may bereduced. Moreover, by encasing a coated implant in a membrane 31 thesmearing or other errant removal of the coating may be diminished by thepresence of the membrane 31.

In its resting state the deformable membrane 31 may have an innerdiameter that is smaller than the outer diameter of the implant 30.Consequently, the deformable membrane 31 in this embodiment should beenlarged in order to place the coated implant 30 into it. By having thedeformable membrane 31 in a state of expansion while it encases theimplant 30 the retroactive forces, to return the deformable membrane 31to its original configuration, can help maintain the positioning of themembrane 31 on the implant 30 during its subsequent handling and use.Alternatively, in a different embodiment, rather than using purecompressive forces to retain the membrane around the implant 30, thedeformable membrane may be ribbed or folded or otherwise configured tofacilitate its retention onto the implant 30.

FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3. Ascan be seen, the encasing hollow deformable membrane 31 of the implant30 is circular and completely encases the implant 30 and its coating 32.The implant 30 in this configuration has not yet been crimped onto acatheter or other carrier device.

FIG. 5 is a side view of the implant 30 after it has been crimped. It isevident in FIG. 5 that the diameter of the implant 30 has been reducedduring the crimping process. During this crimping process forces in thedirection of arrows 51 have been exerted on the membrane 31 to reducethe diameter of the implant 30. As is evident, the coating 32 hasremained intact during this step.

FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 5. WhenFIG. 6 is compared to FIG. 4 the reduction in diameter of the implant 30is clearly evident.

FIG. 7 is a side view of a system that may be used in accord with analternative embodiment of the present invention. In FIG. 7 the carrierdevice 74 may carry an implant 73 on an implant retention region nearits distal end. This implant 73 may be held in place by sox 75 and maybe coated with coating 79. The implant 73 and the carrier device 74 maybe stored within hypo-tube 76 and may be extended out of the hypo-tube76 during the manufacturing process, as shown by arrow 77, in order toplace the membrane 72 around it. The encasing hollow deformable membrane72 may be supported or stretched open by one end of an encasing cage 71.This encasing cage 71 may be a wire cage sized to hold the membraneopen, it may also be a clear tube or any other device adapted to holdthe entrance orifice of the membrane 72 open during the manufacturingprocess.

During the manufacturing process, the carrier device 74 may be insertedinto the entrance orifice of the membrane 72 such that the membrane 72covers both sox 75 and the implant 73. The membrane 72 may then be slidoff of the cage 71 so that the membrane will completely encase theimplant and the sox. Then, after the membrane 72 has been slid off ofthe cage 71, the carrier device may be retracted from the cage 71, nowwith its implant covered with the protective membrane 72.

FIG. 8 is another side sectional view of the carrier device 74 and theencasing membrane 72 of the embodiment of FIG. 7, this time during theactual covering of the implant 73. In this step, as described above, thehypo-tube 76 has been inserted into the opening of the encasing cage 71and the encasing hollow deformable membrane 72. Once the hypo-tube hasbeen inserted into this opening a compressed fluid may be injectedwithin a lumen 81 of the hypo-tube in order to inflate the membrane 72.Then, once the membrane is inflated, the distal end of the carrierdevice 74 may be urged into the membrane 72. The hypo-tube 76 may thenbe pulled away from the cage 71, stopping the flow of compressed airinto the membrane 72 and allowing the membrane to relax and encircle theimplant 73. The entrance orifice of the membrane 72 may also be releasedfrom the cage 71 at this point to allow the membrane to completelyencircle the implant.

FIG. 9 shows a side view of the carrier device 74 after the membrane 72has been released from the cage 71 as described above. As is evident inFIG. 9 the hypotube 76 is no longer inserted into the cage 71 and theimplant 73 is now completely covered by the membrane 72. This implantmay now be removed from the case 71 and may be processed or handled insubsequent steps with the benefit of the protective membrane.

FIG. 10 shows a side view of the carrier device of FIGS. 7-9 after theimplant has been covered and prior to its insertion into a crimpingdevice 100. This crimping device may be a hand held device or amechanical device that may reduce the diameter of the implant 73 to morefirmly secure it to the implant retention region located at the distalend of the carrier device 76. Once the implant has been crimped, themembrane 72 may be removed immediately or it may remain on the implant73 until just prior to its use by a practitioner. Alternatively, ratherthan behaving solely as a crimping mechanism, this device 100 maycomplete both steps by first applying the membrane and then crimping theimplant.

FIG. 11 shows a side view of another alternative embodiment of thepresent invention. In this alternative embodiment an implant device 112has an implant covered in a membrane 110 located at the device's 112distal end. The membrane 110 in this embodiment is shaped like a sleeveand, therefore, has an exit orifice 113. In this embodiment asupplemental cover, here a nylon braided sleeve 111, may be placed overthe membrane 110 to further protect the membrane during subsequentmanufacturing and handling steps.

FIG. 12 is a side view of an implant 123 prior to its insertion into anencasing membrane 126 in accord with another alternative embodiment ofthe present invention. In this embodiment, rather than having compressedair injected through the hypo-tube, two nozzles 121 are positioned nearthe cage 125 entrance such that they may inject pressurized fluid intoentrance orifice of the membrane 126 stretched open by the cage 125.This cage 125 may also contain a brace 122 within it to prevent themembrane 126 from being over-inflated during the process. Therefore, inuse, the membrane may be inflated by the nozzles to allow the implant123 to be inserted into it. Once the implant has been inserted into themembrane, the membrane may then be slid off of the cage. The carrierdevice 124, now carrying the implant, may, then, be removed from thecage 125 for subsequent use and handling. Alternatively, rather thaninjecting fluid to inflate the membrane, the nozzles may be situatedbehind the membrane and may be used to create a vacuum, thereby drawingthe membrane into the cage to enlarge it.

In each of the above embodiments, once the workpiece is ready to beemployed for its intended use, or at any other time deemed appropriateby the user, the protective membrane can be removed. The membrane may beremoved by inflating or alternatively through some destructive methodincluding a zip cord that will sever the membrane when it is pulled.

A protective membrane as employed in the various embodiments of thepresent invention can be manufactured from a number of materials,including latex, silicone, polyurethane, chloroprene or nitrile. It mayalso have a thickness preferably between 0.3 mm and 0.6 mm and containmaterials that are flexible and allow for the transmission of forces tothe workpiece during the workpiece's manufacture. In one embodiment, themembrane is a tube with a single opening while in another embodiment themembrane is a sleeve with openings on both ends.

The range of medical implants that may be protected by these membranesinclude: expandable and self-expanding stents, balloon catheters,vena-cava filters, aneurysm coils, stent-grafts, a-v shunts,angio-catheters, and PICC's. Moreover, the coatings employed may containpaclitaxel as well as other therapeutics, which include, for example:pharmaceutically active compounds, proteins, cells, oligonucleotides,ribozymes, anti-sense oligonucleotides, DNA compacting agents,gene/vector systems (i.e., any vehicle that allows for the uptake andexpression of nucleic acids), nucleic acids (including, for example,recombinant nucleic acids; naked DNA, cDNA, RNA; genomic DNA, cDNA orRNA in a non-infectious vector or in a viral vector and which furthermay have attached peptide targeting sequences; antisense nucleic acid(RNA or DNA); and DNA chimeras which include gene sequences and encodingfor ferry proteins such as membrane translocating sequences (“MTS”) andherpes simplex virus-1 (“VP22”)), and viral liposomes and cationic andanionic polymers and neutral polymers that are selected from a number oftypes depending on the desired application. Non-limiting examples ofvirus vectors or vectors derived from viral sources include adenoviralvectors, herpes simplex vectors, papilloma vectors, adeno-associatedvectors, retroviral vectors, and the like. Non-limiting examples ofbiologically active solutes include anti-thrombogenic agents such asheparin, heparin derivatives, urokinase, and PPACK (dextrophenylalanineproline arginine chloromethylketone); antioxidants such as probucol andretinoic acid; angiogenic and anti-angiogenic agents and factors; agentsblocking smooth muscle cell proliferation such as rapamycin,angiopeptin, and monoclonal antibodies capable of blocking smooth musclecell proliferation; anti-inflammatory agents such as dexamethasone,prednisolone, corticosterone, budesonide, estrogen, sulfasalazine,acetylsalicylic acid, and mesalamine; calcium entry blockers such asverapamil, diltiazem and nifedipine;antineoplastic/antiproliferative/anti-mitotic agents such as paclitaxel,5-fluorouracil, methotrexate, doxorubicin, daunorubicin, cyclosporine,cisplatin, vinblastine, vincristine, epothilones, endostatin,angiostatin and thymidine kinase inhibitors; antimicrobials such astriclosan, cephalosporins, aminoglycosides, and nitrofurantoin;anesthetic agents such as lidocaine, bupivacaine, and ropivacaine;nitric oxide (NO) donors such as linsidomine, molsidomine, L-arginine,NO-protein adducts, NO-carbohydrate adducts, polymeric or oligomeric NOadducts; anti-coagulants such as D-Phe-Pro-Arg chloromethyl ketone, anRGD peptide-containing compound, heparin, antithrombin compounds,platelet receptor antagonists, anti-thrombin antibodies, anti-plateletreceptor antibodies, enoxaparin, hirudin, Warfarin sodium, Dicumarol,aspirin, prostaglandin inhibitors, platelet inhibitors and tickantiplatelet factors; vascular cell growth promoters such as growthfactors, growth factor receptor antagonists, transcriptional activators,and translational promotors; vascular cell growth inhibitors such asgrowth factor inhibitors, growth factor receptor antagonists,transcriptional repressors, translational repressors, replicationinhibitors, inhibitory antibodies, antibodies directed against growthfactors, bifunctional molecules consisting of a growth factor and acytotoxin, bifunctional molecules consisting of an antibody and acytotoxin; cholesterol-lowering agents; vasodilating agents; agentswhich interfere with endogenous vascoactive mechanisms; survival geneswhich protect against cell death, such as anti-apoptotic Bcl-2 familyfactors and Akt kinase; and combinations thereof. Cells can be of humanorigin (autologous or allogenic) or from an animal source (xenogeneic),genetically engineered if desired to deliver proteins of interest at theinjection site. The delivery medium is formulated as needed to maintaincell function and viability. Modifications are routinely made by oneskilled in the art.

Polynucleotide sequences useful in practice of the invention include DNAor RNA sequences having a therapeutic effect after being taken up by acell. Examples of therapeutic polynucleotides include anti-sense DNA andRNA; DNA coding for an antisense RNA; or DNA coding for tRNA or rRNA toreplace defective or deficient endogenous molecules. The polynucleotidesof the invention can also code for therapeutic proteins or polypeptides.A polypeptide is understood to be any translation product of apolynucleotide regardless of size, and whether glycosylated or not.Therapeutic proteins and polypeptides include as a primary example,those proteins or polypeptides that can compensate for defective ordeficient species in an animal, or those that act through toxic effectsto limit or remove harmful cells from the body. In addition, thepolypeptides or proteins that can be injected, or whose DNA can beincorporated, include without limitation, angiogenic factors and othermolecules competent to induce angiogenesis, including acidic and basicfibroblast growth factors, vascular endothelial growth factor, hif-1,epidermal growth factor, transforming growth factor .alpha. and .beta.,platelet-derived endothelial growth factor, platelet-derived growthfactor, tumor necrosis factor .alpha., hepatocyte growth factor andinsulin like growth factor; growth factors; cell cycle inhibitorsincluding CDK inhibitors; anti-restenosis agents, including p15, p16,p18, p19, p21, p27, p53, p57, Rb, nFkB and E2F decoys, thymidine kinase(“TK”) and combinations thereof and other agents useful for interferingwith cell proliferation, including agents for treating malignancies; andcombinations thereof. Still other useful factors, which can be providedas polypeptides or as DNA encoding these polypeptides, include monocytechemoattractant protein (“MCP-1”), and the family of bone morphogenicproteins (“BMP's”). The known proteins include BMP-2, BMP-3, BMP-4,BMP-5, BMP-6 (Vgr-1), BMP-7 (OP-1), BMP-8, BMP-9, BMP-10, BMP-11,BMP-12, BMP-13, BMP-14, BMP-15, and BMP-16. Currently preferred BMP'sare any of BMP-2, BMP-3, BMP-4, BMP-5, BMP-6 and BMP-7. These dimericproteins can be provided as homodimers, heterodimers, or combinationsthereof, alone or together with other molecules. Alternatively or, inaddition, molecules capable of inducing an upstream or downstream effectof a BMP can be provided. Such molecules include any of the “hedgehog”proteins, or the DNA's encoding them.

These therapeutic agents can be used, for example, in any applicationfor treating, preventing, or otherwise affecting the course of a diseaseor tissue or organ dysfunction. For example, the methods of theinvention can be used to induce or inhibit angiogenesis, as desired, toprevent or treat restenosis, to treat a cardiomyopathy or otherdysfunction of the heart, for treating Parkinson's disease or a strokeor other dysfunction of the brain, for treating cystic fibrosis or otherdysfunction of the lung, for treating or inhibiting malignant cellproliferation, for treating any malignancy, and for inducing nerve,blood vessel or tissue regeneration in a particular tissue or organ.

While various embodiments of the present invention are disclosed aboveother embodiments are also possible without straying from the spirit andscope of the present invention.

1. A coated stent in combination with a device for crimping the coatedstent and a system for protecting the coated stent during crimping, thecombination comprising: a catheter, the catheter having a proximal endand a distal end; and a stent mounted on the distal end of the catheter,the stent coated with a coating, the coating positioned on an exposedsurface of the stent, the stent adapted to be crimped on the catheterfrom a first configuration wherein the stent has a first diameter to asecond configuration wherein the entire stent has a second diametersmaller than the first diameter; an encasing hollow deformable membrane,the membrane, in an unexpanded resting state, defining a cavity having across-section that is smaller than the external cross-section of thestent when the entire stent is in its second configuration; and a devicefor crimping the coated stent on the catheter from the firstconfiguration to the second configuration; wherein the combination has afirst positional arrangement while the stent is in the firstconfiguration, wherein in the first positional arrangement the stent iscovered by the membrane and is inserted in the crimping device, andwherein the combination has a second positional arrangement after thestent has been crimped to the second configuration, wherein in thesecond positional arrangement the stent remains covered by the membraneand the stent is no longer inserted in the crimping device; and whereinthe membrane is adapted to be stretched to an expanded state tofacilitate placing the membrane around the stent when the stent is inits first configuration and then released so that the membrane contractsaround the stent.
 2. The combination of claim 1 further comprising anencasing cage adapted to hold the encasing hollow deformable membrane inthe expanded state to facilitate placing the encasing hollow deformablemembrane around the stent.
 3. The combination of claim 1 furthercomprising a hypo-tube adapted to facilitate enlargement of the encasinghollow deformable membrane to the expanded state to facilitate placingthe encasing hollow deformable membrane around the stent.
 4. Thecombination of claim 1 further comprising a nozzle adapted to facilitateenlargement of the encasing hollow deformable membrane to the expandedstate to facilitate placing the encasing hollow deformable membranearound the stent.
 5. The combination of claim 1 wherein the deformablemembrane includes a zip cord, the zip cord having an accessiblegraspable portion extending from the deformable membrane.
 6. Thecombination of claim 1 wherein the deformable membrane has acylindrically shaped portion.
 7. The combination of claim 1 wherein thedeformable membrane defines a vessel with a single orifice.
 8. Thecombination of claim 1 wherein the deformable membrane has a thicknesssubstantially between 0.3 mm and 0.6 mm.
 9. The combination of claim 1wherein the catheter is a balloon catheter.
 10. The combination of claim1 wherein the deformable membrane includes an external coating along anoutside exposed surface of the deformable membrane.
 11. The combinationof claim 1 wherein the deformable membrane is covered with a protectivecovering.
 12. The combination of claim 11 wherein the protectivecovering is a monofilament nylon braided sleeve.